Effects of inflammatory changes in the middle ear mucosa on middle ear total pressure

CONCLUSIONS: Inflammation of the middle ear mucosa leads to inhibition of transmucosal carbon dioxide (CO2) diffusion. Furthermore, CO2 diffusion is inhibited more severely in ears with a histologically higher grade of inflammation. OBJECTIVES: To investigate the effect of inflammatory changes in the middle ear mucosa on transmucosal gas exchange, and the relationship between the histologic inflammation grade of the middle ear mucosa and the middle ear total pressure (METP). MATERIALS AND METHODS: Twenty-six rabbits were used for this study. Changes in the METP and the oxygen partial pressure in the middle ear (PmO2) were measured in the otitis media group and the untreated group, and were compared between the two groups. Inflammatory changes in the middle ear mucosa were classified into four grades histologically, and the relationship between the histologic inflammatory grade and the maximum METP was examined. RESULTS: The maximum METP in the otitis media group was significantly decreased compared with the untreated group (p < 0.05), but there was no difference between the two groups in the rate of decrease of the PmO2. Furthermore, the maximum METP in grade III inflammation was significantly decreased compared with that in grade II inflammation (p < 0.05).